Please add features to the Steel HR to measure and track hydration levels. This is already being done by several available devices. See, for example: https://www.wearable-technologies.com/2018/03/drink-much-get-to-know-these-new-wearables-for-hydration/
This became important recently when my blood pressure was unexpectedly very high. I determined the cause was dehydration. It would have been excellent if my Steel HR, my Body+ scale and my BPM connect had integrated blood pressure data and hydration data to alert me to the problem, identified the cause, and suggested actions I can take.